Are you using a constant literal for the val? The default kinds for constant literals is 4, but val is expecting a kind of 8. Hence, you need to an "_8" to the end of the literal in order set the kind as 8.

Note that it did some checking and while we've had 64-bit atomics in since we added CUDA 4.0, it looks there was a issue with the 64-bit atomicadd where you'll get a undefined identifier error (TPR#18767). This issue will be resolved in the next release.

Hopefully soon. It's already be delayed by several weeks due to unforeseen problems. I was told this morning, barring more issues in our final QA testing, it should be out later this week or early next.